This invention relates to a system for retaining a battery on a printed circuit board inside battery driven electrical equipment such as an electric razor.
Many compact electrical devices, such as the electric razor, which are powered by dry cells or rechargeable batteries have been known for some time. Electrical equipment driven by dry cell batteries are provided with a battery compartment allowing battery installation and removal to facilitate spent battery exchange. On the other hand, electrical equipment driven by rechargeable batteries are often assembled with internal rechargeable batteries, a rechargeable battery charging circuit, and AC plug blades for connecting to commercial power as a source of power for charging. This is done because rechargeable batteries can be used repeatedly with recharging. When rechargeable batteries in this type of electrical equipment become discharged as a result of driving the load, they can be recharged by inserting the AC plug blades into an electrical outlet without removing the batteries from inside the electrical equipment. Recharging renews the batteries to full charge able to again drive the electrical equipment. In this manner, since rechargeable batteries can be used repeatedly, there is no need to exchange batteries, no need to install or remove batteries, and the batteries can be permanently built-in to the electrical equipment. Therefore, the electrical equipment is easy to use and its structure is simplified since no battery compartment is required.
FIG. 1 shows an oblique view of a rechargeable battery with conducting tabs 2 welded to its electrode regions, and FIG. 2 shows an oblique view of a rechargeable battery mounted on a printed circuit board. Part number 1 is a rechargeable nickel cadmium battery. This battery 1 is provided with a positive (+) and negative (-) electrode region, and a conducting tab 2 is spot welded to each electrode region. As mentioned previously, when the nickel cadmium battery is used in electrical equipment such as an electric razor, there is no need to remove or replace the battery 1 inside the electrical equipment. Therefore, the conducting tabs 2 can be soldered directly to the printed circuit board 3 housed within the electrical equipment. The conducting tabs 2 are made for the purpose of soldering to a printed circuit board 3. Space on the printed circuit board 3 is allocated for the battery 1 and slits 4 through the board are provided for the conducting tabs 2 at both ends of the battery. The conducting tabs 2 of the battery 1 are inserted into the slits 4 of the printed circuit board 3 and the battery 1 is retained on the top of the printed circuit board. The conducting tabs 2 are bent over on the reverse side of the printed circuit board 3 and soldered to the surface of the board. In this fashion the battery 1 is fixed to the printed circuit board 3 and housed within the electrical equipment.
However, in recent years rechargeable batteries such as nickel cadmium batteries that have exceeded their lifetime and become non-functional, have been separated from other discarded waste and recycled to protect the environment. However, as shown in FIG. 2, a nickel cadmium battery 1 soldered to a printed circuit board 3 cannot be removed without using a special tool such as fine tipped diagonal cutters to cut the conducting tabs 2. For this reason, recovery of only the nickel cadmium batteries 1 is an extremely difficult problem.
This problem can be solved by providing a battery compartment that allows insertion and removal of batteries in the same manner as prior art electrical equipment powered by dry cell batteries. However, a removable dry cell battery compartment requires a structure to accurately retain batteries in proper position and spring-loaded contacts to press against the electrodes of the properly positioned batteries. To retain batteries in their proper positions, it is necessary to surround them with wall-like structures. Battery compartments of many electrical devices have battery cases or enclosures in which the batteries are retained in their specified positions. For this reason, a large amount of the electrical equipment space must be devoted to the battery compartment region and compact design is made difficult. Furthermore, the removable dry cell battery compartment has the drawback that electrical contact problems arise easily between the spring-loaded contacts and the battery electrodes. Strengthening the pressure of the spring-loaded contacts against the electrodes is effective in reducing contact problems. However, this makes insertion and removal of the dry cell batteries difficult. Further, when both battery electrodes are strongly pressed on by spring-loaded contacts, the batteries are easily dislodged from their specified battery case positions causing contact problems.
The object of present invention is to solve the previously mentioned problems by offering a battery retaining system that provides reliable electrical contact and reliable printed circuit board (or other structure) attachment for a battery housed internally in an electrical apparatus, and in addition makes the battery easily removable.